The invention concerns an apparatus for converting solar energy into heat, comprising a solar collector made up of a plurality of collector elements which are attachable to the outside of a building or the like, are mutually couplable, and are capable of being connected to a heat transfer fluid circulation system, wherein each collector element comprises a heat transfer fluid channel with a transparent cover.
A disadvantage found with known apparatuses of this type is that while there is no problem in extracting energy during the time of year when the temperature of the heat transfer fluid is above a certain value, when the temperature of the fluid falls below a certain minimum value the apparatus must be shut off. The underlying problem is to refine prior art apparatuses in such a way that energy can be extracted even under poor weather conditions or at relatively low ambient temperatures.